Penetration of the LCLS Injector Shield Wall at Sector 20

Dowell, D

SLAC National Accelerator Laboratory

关键词: Light Sources;    Radiation Streaming;    Electron Beams;    43 Particle Accelerators;    Waveguides;   

DOI  :  10.2172/1000318
RP-ID  :  SLAC-TN-10-085
RP-ID  :  AC02-76SF00515
RP-ID  :  1000318

美国|英语

来源: UNT Digital Library

【 摘 要 】

Penetrations through the LCLS injector shield wall are needed for the alignment of the accelerator, a diagnostic laser beam and utilities, and are shown in figure 1. The 1-inch diameter LCLS injector beam tube is blocked by the PPS stopper when the injector side of the wall is occupied. The two 3-inch diameter penetrations above and to the left of the beam tube are used by Precision Alignment and will be open only during installation of the injector beamline. Additional 3-inch diameter penetrations are for laser beams which will be used for electron beam diagnostics. These will not be plugged when the injector occupied. Other penetrations for the RF waveguide and other utilities are approximately 13-inch from the floor and as such are far from the line-of-sight of any radiation sources. The waveguide and utility penetrations pass only through the thicker wall as shown in the figure. The principal issue is with the two laser penetrations, since these will be open when the linac is operating and people are in the LCLS injector area. A principal concern is radiation streaming through the penetrations due to direct line-of sight of the PEP-2 lines. To answer this, fans of rays were traced through the 3-inch diameter laser penetrations as shown in Figures 2 and 3. Figure 2 gives the top view of the shield walls, the main linac and PEP-2 lines, and the ray-fans. The fans appear to originate between the walls since their angular envelope is defined by the greatest angle possible when rays are just on the 3-inch diameter at the inner most and outermost wall surfaces. The crossovers of all possible rays lie half way between these two surfaces. As the end-on view of Figure 3 clearly shows, there is no direct line-of-sight through the laser penetrations of the PEP-2 or linac beamlines.